As PGE.sub.2 agonist, many compounds have been known including PGE.sub.2 per se. However, no compounds which antagonize for PGE.sub.2 or inhibit PGE.sub.2 activity (PGE.sub.2 antagonist) have been known until now.
PGE.sub.2 has been known as metabolite in the arachidonate cascade. It has been known that PGE.sub.2 has uterine contractile activity, pain-inducing effect, promoting effect of digestive peristalsis, awaking effect, suppressive effect of gastric acid secretion, hypotensive activity, blood platelet inhibition activity etc. It is expected that the following activities are possessed according to antagonizing or agonizing these activities of PGE.sub.2.
To antagonize PGE.sub.2 means to suppress the effects above mentioned, so PGE.sub.2 antagonists are considered to inhibit uterine contraction, to have analgesic action, to inhibit digestive peristalsis, to induce sleep. Therefor, PGE.sub.2 antagonists are considered to be useful for the prevention of abortion, or as analgesics, antidiarrheals or sleep inducer.
To agonize for PGE.sub.2 means to promote the effects above mentioned, so PGE.sub.2 agonists are considered to stimulate uterine contraction, to promote digestive peristalsis, to suppress gastric acid secretion, to lower blood pressure or to inhibit blood platelet aggregation. Therefor, PGE.sub.2 agonists are considered to be useful as abortient, cathartics, and antiulcer, anti-gastritis, antihypertensive or antithrombosis agefnts.